System of control.



APPLICATION FILED SEPT, 3, 1907- WITNESSES:

iNVENTOFI V flmyfl Jamm UNITED STATES PATENT ornro'n;

EZFNRY D. JAMES, OF PITTSBURG, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

SYSTEM OF CONTROL.

Specification o! Letters Patent Patented July 7, 1908.

Original application filedgMay 6, 1907, Serial No; 372,139. Divided and. this application filed September 3, 190

' Serial No. 391,213.

and useful Improvement in Systems of Control, of which the following is a specification,

this application being a division of my application, Serial No. 372,139, filed May 6, 1907.

My invention'relates to systems of control for electric motors, andparticularly to such as embody a plurality of separately-actuated switches adapted to be operated in succes sion and to thereby effect automatic acceleration in the speed of a motor.

' p The object of my invention is to so arrange lithe circuits of a system of control of the character indicated that a lower voltage may he applied to the operating or controlling I magnet-windings of the separately-actuated switches-than that of the circuit from which the motor is supplied, and also so that but a single voltage'sreducing resistance need be Jemployed; '25

The single" figure of the accompanying drawings is 'a diagrammatic view of a system of control that embodies my invention.

In the system illustrated, a motor armature 1 is connected to a supply circuit 23, in series'with a resistance comprisingsections 4, 5 and 6, by means of a switch 7, and the resistance sections may be shunted successively by switches 8, 9 and 10; The sWitChes 7 to 10,- inclusive, are provided, respectively, with operating or controlling magnet windings 11, 1'2, 13 and 14, one-termin'al of each of the three latter windings being connected, respectively, to terminals of the resistance sections 4, 5 and 6. The other terminals of the magnet windings 12, 13 and 14 are adapted to be connected by means of interlocking switches 15, 16 and 17, respectively, that are associated with the switches 7, 8 and 9, to suitable points in a resistance 18 that is connected to the circuit 23. A manually-operated switch 19 is employed for the purpose of connecting one terminal of the magnet winding 11 also to a suitable point in the resistance 18.

In the operation of the system, switch 19 is first closed and the me, not winding 11 is then connected between t e point 20 in the resistance 18 and supply conductor 3, thievoltermined value.

equal to the difference of potential between the point 20 and the conductor 3, which will be less than thatof the-circuit 2-3 by an amount e ual to the difl'eren'ce-of potential between t e point 20 and the conductor 2. When the switch 7 closes, the interlocking switch 15 also closes and completes the circuit of the magnet winding 12 which is then connected between the point 20 ofthe re.

sistance 18 and one terminal of resistance section 4, As the motor increases in speed, the current traversing the resistance decreases and, consequently, also the drop of potential over the resistance section 4. -As

the drop of potential over the resistance sec-' tion 4 decreases, the voltage ap )lied to the winding 12 increases and when t is attains a predetermined value, the magnet winding 12 ecomes sufiiciently energized to cause the switch 8 to close. When the switch 8 closes, the switch 16 also closes and establishes the circuit ofthe winding 13 which becomes sufficiently energized to cause closure of the switch .9 when the drop of potential over the resistance section 5 has decreased to a rede- The switch 10 will li ewise be caused to'close after the switch 9 has closed, when the drop of-potential over the resistance section 6 has decreased to a predetermined value. A

As the magnet windings of the switches are connected successively in circuit the amount of current traversing the resistance 18 increaseaand, consequently, the-difference of potential between the conductor 2 and the point in the resistance to which the magnet windings are connected increases, so that if it is desired to use identical windin s for operat-,

ing the switches it will usually e found-flesirable to connect the magnet windings to difierent points 20, 21 and 22 of theresiste ance 18, as shown,"siidh thatthe-difierenoe of potential between the'conductor'il and the point of connection of the magnet'winding with the resistance will remain substantially constant. Thus, a materially lower voltage may be applied to the magnet windin s of the switches than that of the circuit to w 'ich the motor armature is connected, and, at the same time, the operation of the-switches may be caused to depend upon the dropiof potential over successlve sections of'the resistance or upon the counter-electromotive force oil the motor, and this result is attained by the use of a single voltage-reducing resistance instead of one for each magnet winding, as has heretofore been necessary.

I claim as my invention.

1. The combination Witha supply circuit and a resistance connected thereto, of a motor, a resistance in the armature circuit thereof, means for removing the resistance from. the armature circuit comprising a plurality of magnet windings,- and means for connecting the magnet windings respectively between, and to different points of, the said resistances.

2. The combination with a supply circuit and a resistance connected thereto, of a motor, a resistance in the armature circuit thereof, means for removing the resistance from the armature circuit comprising. a plurality otmagnet windings, and means for connecting the magnet windings in succ'es sion between, and to different points of, the said resistances.

3. The combination with a supply circuit and a resistance connected thereto, of a motor, a subdivided resistance in the armature circuit thereof, means for removing the resistance from the armature circuit comprismg a plurality of magnet windings connecteeaee and a resistance connected thereto, of a motor, a resistance in the armature circuit thereof, andv means tor removing the resistai'ice from the armature circuit comprising a p1urality of magnet windings arranged to connected between, and to different points oi,

the said resistances.

5. The combination with a supply circuit, and a resistance connected thereto, of a motor, aresistance in the armature circuit thereof, a plurality of switches for removing the resistance from the armature circuit, and controlling magnet windings arranged to be conneetedbetween, and to diiierentpoi is the said resistances.

In testimony whereof, l" he subscribed my name this 21st day of 1; 1907.

HENRY D. JnE ilQki. l/Vitnesses:

H. A. S-rnnn, BLRNEY HINES. 

